Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth. UWB microwave systems are finding application in the form of impulse radio, as well as respiratory, cardiovascular and other sensing/monitoring applications. The Federal Communication Commission (FCC) defines UWB as an intentional radiator with an instantaneous 10 dB-fractional and total bandwidth of at least 0.2 and 500 MHz, respectively. This bandwidth is achieved primarily by radiating ultra short pulses that are derived from a basic Gaussian pulse shape. The FCC requires a magnitude response that varies between 0 dBm and −23 dBm within a 0.5 GHz to 3.5 GHz band. To maximize the energy within this band, pulse shaping is required. This shaping is achieved by differentiating or shaping the Gaussian pulse.
Solid-state UWB pulse shaping has been achieved using Gallium Arsenide (GaAs) Metal-Semiconductor Field-Effect Transistors (MESFETs), non-linear transmission lines, short-circuit stubs, and resistive-reactive circuits. In these applications, the waveform response to circuit reactance is fundamental to pulse formation. As such, the reactive elements form a simple resistor-capacitor (RC) or resistor-inductor (RL) network. In an RC network, waveform differentiation occurs in a process of charging and discharging the circuit capacitance. The capacitor builds up charge in accordance with the RC time constant (τrc where τrc=RC), which defines the time required for a signal to rise to 63.2% of its full value. When used in conjunction with a 50Ω load, the RC time constant requires less than a 20 pF capacitance (C) for shaping sub-nanosecond pulses.
Accordingly, what is needed in the art is a system and method for improved simultaneous shaping of sub-nanosecond UWB waveform pulses.